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I am building a new house and am planning to hardwire network cables into each room.

Can I run CAT5/6 cables parallel to electrical wires without introducing any general safety issues or losing much in connection quality?

Wiring runs for up to 25 metres from patch panel and distribution board in garage to rooms.

My research indicates that is should be fine if they are in separate conduits or if the CAT cables are shielded.

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migrated from electronics.stackexchange.com Jan 16 '12 at 21:52

6 Answers

up vote 17 down vote accepted

While a shielded Cat5/6 cable is designed to protect itself from outside interferance, it isn't recommended to run them side-by-side to your electrical wiring. Typical is to run electrical down one stud and the Cat5/6 down a different stud. Basically do the same as you would for telco.

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Thanks for the answer. Apologies for my ignorance; do you mean conduit with "stud"? – Martin Jan 16 '12 at 9:18
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I believe he's suggesting using a different stud; not the other side of the same one, for (e.g.) 16" of separation, not 1-1/2". – JRobert Jan 16 '12 at 16:33
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That makes sense. I'm from South Africa and we build using bricks and mortar. No wood at all. So the wiring and cables place inside PVC pipes and are then covered with concrete – Martin Jan 17 '12 at 13:04
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archive.org/details/gov.law.nfpa.nec.2011 While this is a link, and therefore link rot may set in, the NEC is available for download through Archive.org. 800.133(A)(2) states that Communications wires and cables shall be separated by at least 50mm (2 in.) from conductors of any electrical light, power, Class 1 non-power-limited fire alarm or medium-power network-powered broadband communications circuits. Exceptions are if separate raceways or conduit are used for separating the communications cables/wires from the power conductors. – Fiasco Labs Nov 4 '12 at 18:12
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While Ethernet falls under low power communications and 800 rules, running POE (Power Over Ethernet) will change its classification to Class 2 or Class 3 power and require consulting 725 rules for its installation. – Fiasco Labs Nov 4 '12 at 18:23
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up vote 11 down vote

You want to keep low voltage and high voltage separate so that stray nails, screws, and staples installed by less attentive individuals in the future can't puncture the cables and turn your low voltage wire into high voltage. There is always a chance some idiot is going to stick something electrically conductive where he ought not, and he probably shouldn't pay with his life for the mistake. (Nor should the home owner employing the idiot.) That's good to keep in mind even outside of construction/home improvement situations.

I have no idea what code actually says, but conduit is probably sufficient for the task, and shielded cable isn't. Distance would be the best option.

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800.133(A)(2) states that Communications wires and cables shall be separated by at least 50mm (2 in.) from conductors of any electrical light, power, Class 1 non-power-limited fire alarm or medium-power network-powered broadband communications circuits. -> Their concern is not with electrical interference, merely power safety. More distance is better. – Fiasco Labs Nov 4 '12 at 18:14
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I think not a good idea, every power cable creates an electromagnetic field http://en.wikipedia.org/wiki/Electromagnetic_induction which will influence the other cables at least will lead to disturbances and errors.

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What does your program for calculating voltage drop in industrial pumping stations have to do with running data wiring through a wall? – Niall C. Jan 17 '12 at 19:07
I've edited out the irrelevant part of the answer. – ChrisF♦ Jan 18 '12 at 9:52
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Inverse square law says that the fields decrease rapidly with distance. The strength of the fields is dependent on the voltage and amperage in the power cables. Higher current requires greater separation. – Fiasco Labs Nov 4 '12 at 17:40
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As others have mentioned, there could be some interference. Most likely there is not a safety issue here if you are running parallel to standard plastic-sheathed NM / romex wire, but you may see reduced speeds. It's certainly not against code. You should at least use CAT 5e over CAT 5, as it is shielded better and can almost work at Gigabit speeds. CAT 6a would be your best bet, but probably a little overkill for you. When I built, I ran 5e in my house, and tried to keep it away from the the electrical as much as I could. There was some crossover and parallel runs, but it was kept at a min and I have been getting near gigabit speeds.

Note, manufactures have been using the term CAT6e, which does not appear to be a true spec. Seems like they are loosely using that as CAT6 with extra shielding. CAT6a on wikipedia.

Here is an article I found: differences between cat5 cat5e cat6 and cat6e cables

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why the downvotes? – mohlsen Jan 18 '12 at 3:53
There is no such thing as cat 6e. There is CAT 6 and 6a. – Steven Jan 18 '12 at 3:57
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also, it is in part a safety issue. and you should always be incredibly hesitant to dismiss something as not being a safety issue. – Jay Kominek Jan 18 '12 at 4:19
didn't realize 6e was not a "true standard", although if you google it everyone sells it. Updated that to clarify. Also changed the safety comment. – mohlsen Jan 18 '12 at 13:31
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its very simple just don't put your Ethernet cables near any of power cables make it far away with 10 to 12 " and for any future installing you put your cables inside a PVC pipe inside the wall this way it's more easy if you want to replace any cables in the future.

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The actual separation is about 4-inches, iirc. This information can be found but it's been a while since I installed mine. You can run data cables closer but only if they are perpendicular to the electric lines. Of course, the farther away the better. – Rob Nov 4 '12 at 14:19
up vote -1 down vote

Be sure to use cables rated for in-wall Riser (CMR) use. That's a safety issue in the event of a fire. Use Plenum is rarely required in homes.

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Plenum (CMP) is only required if the cable is installed in a plenum space. Riser (CMR) is required for between floors so long as the space is not used for environmental air. The only differences really are plenum is self-extinguishing and low-smoke. – gregmac Jan 18 '12 at 0:06
Also, this is not a very good answer to the actual question, and would have been better as a comment. – gregmac Jan 18 '12 at 0:07
@gregmac: Updated, thanks. – Brian Carlton Jan 18 '12 at 0:19

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